Gonadotropin-releasing hormone (GnRH) is a neurohomrone responsible for the activation and maintenance of reproduction. Neurons that synthesize GnRH must undergo complex maturational processes during development to become a functional system capable of supporting reproduction. Once mature, the GnRH system also needs to remain functional for an appropriate duration to ensure the propagation of offspring. Thus, one's reproductive health is critically dependent on factors that orchestrate the formation and maintenance of the GnRH system. The goal of the proposed study is to understand how a group of signaling molecules, fibroblast growth factors (FGFs), and their receptors (FGFRs) regulate the developmental maturation and postnatal functionality of the GnRH system. A number of transgenic mouse models, each lacking a distinct component of the FGF signaling system, will be used to investigate if these deficiencies result in the aberrant formation or maintenance of the GnRH system, ultimately leading to sterility. In vitro culture methods, morphological analysis, gene expression studies, electrophysiology, and whole animal manipulation will be utilized for this purpose. This research is highly relevant to public health because mutations on one of the FGFRs lead to human disorders characterized by reproductive failure. Understanding how FGFs and FGFRs regulate the GnRH system could provide important insights into the nature of GnRH system disruption in these individuals. In addition, it will reveal if mutations on other genes encoding FGFs/FGFRs are also candidates for these human disorders.